In this renewal application, we propose to investigate further: the ultrastructure of the penile erection tissue; impotence due to arterial insufficiency and venous leakage; and the feasibility of intraoperative electrostimulation of the cavernous nerves. The results obtained will then be applied to the prevention and treatment of impotence by neurostimulation in patients with neurogenic impotence. In addition, we hope to perfect the treatment of vasculogenic impotence with new procedures that will correct arterial insufficiency and venous incompetence. Animal studies will include: 1. Electronmicroscopic study of normal and ischemic penile tissue to examine the adrenergic and cholinergic nerve terminals and those for which VIP is the neurotransmitter. 2. Creation of an animal model to determine whether chronic arterial insufficiency results in venous leakage and whether ligation of the penile veins improves erection. 3. Anastomosis of the internal pudendal artery to the cavernous vein to determine whether this revascularization technique improves blood flow to the ischemic corpus cavernosum. Human studies will include: 1. Electronmicroscopic studies and examination of terminal nerve endings in biopsy specimens obtained from patients undergoing insertion of a penile prosthesis. 2. Intraoperative neurostimulation in patients undergoing radical cystectomy or radical prostatectomy for cancer of the bladder and prostate. 3. Implantation of an erection stimulator in selected spinal-cord- injury patients with neurogenic impotence.